/Engine/Plugins/Runtime/GeometryProcessing/Source/DynamicMesh/Public/Operations/MeshGeodesicSurfaceTracer.h
The same polar point (r, AngleR) can be described by an infinite number of alternative angles, each offset by some multiple of 2pi, i.e. (r, AngleR + n * 2Pi). This selects the unique angle that falls in the [0,2pi) range.
namespace UE { namespace Geometry { static double UE::Geometry::AsZeroToTwoPi ( double AngleR ) } }